Exemplary aspects of the present invention relate to an optical device including plural light modulators to modulate plural color lights with respect to each color light according to image information and to form optical images and to a light combining device having plural luminous flux incident end surfaces opposed to the respective light modulators to combine the optical images formed in the respective light modulators, and a projector including the optical device.
Related art projectors are utilized for presentation application in conferences, academic conferences, and exhibitions or the like, and for home theater application.
A related art 3-LCD projector includes a color separation system to separate luminous fluxes output from a light source lamp into color lights of three colors of red, green, and blue using a dichroic mirror, three liquid crystal panels (light modulating devices for light modulation in light modulators) to modulate the separated luminous fluxes according to image information with respect to each color light, an optical device having a cross dichroic prism (light combining device) to combine the luminous fluxes modulated in the respective liquid crystal panels, and a projection lens to enlarge and project a color optical image formed by the optical device on a screen.
In an optical device incorporated into such a projector, the ease of assembly is created by integrally assembling optical conversion elements, such as liquid crystal panels and polarizing plates in the cross dichroic prism.
For example, the three liquid crystal panels are accommodated in recessed portions of holding frames and pressingly fixed with fixing plates, respectively. To the luminous flux incident end surfaces toward the three directions on the sides of the cross dichroic prism, fixing frame plates to finally fix the liquid crystal panels are attached, and intermediate frame plates for temporal fixation are secured to the fixing plates by screws. See Publication of Japanese Patent Application No. Hei-10-10994 (FIG. 7).
In this example, the liquid crystal panel is temporarily fixed by inserting pins protruded from four comers of the intermediate frame plates into and engaged with holes of the holding frames. Pairs of wedges are pressed into space between the liquid crystal panels and the holding frames in this condition. Finally, these wedges are fixed to the fixing members by adhesive bonding.
In the case where the optical device is incorporated into the projector, it is necessary to locate the respective liquid crystal panels in positions of the back focus of the projection lens. Further, since every single pixel of the projection image is formed by additive color mixing of three primary colors of red, green, and blue, it is necessary to obtain finer images to prevent pixel displacement by adjusting the relative positions of the respective liquid crystal panels with high accuracy.
Therefore, in the related art, positioning is performed by making adjustments in the z direction along an optical axis according to the insertion amounts of the respective pins and respective wedges, while moving the fixing plates adhered to the luminous flux end surfaces of the cross dichroic prism in the X direction, Y direction, and rotation directions thereof. See Publication of Japanese Patent Application No. Hei-10-10994 (FIG. 7).
Higher brightness of such a projector is being promoted, and accordingly, cooling of the optical devices, such as liquid crystal panels becomes an important challenge. Here, as a forced cooling method, air taken from the outside has been blown on these optical devices by a fan. See Publication of Japanese Patent Application No. Hei-10-10994 (FIG. 7).